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Class D Switching Power Amplifiers and Power D/A conversion

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Old 8th October 2007, 02:51 PM   #21
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All this crap because of one persons question as to where to find an amplifier.

Why all the bickering !

Chill out people.

Andrew
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Old 8th October 2007, 04:31 PM   #22
BWRX is offline BWRX  United States
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Quote:
Originally posted by Eva
Note that there are other companies in Asia and India that seem to be selling clones of amplifier models made by well known European and North American firms.
Quote:
Originally posted by Workhorse
EVITA THIS IS BLATANT LIE IN THE CASE OF INDIA.
Eva, there are sleazy companies all over the world (not just in Asia and India) that clone or copy both good and bad designs from well known companies.

Kanwar, there's no need to YELL or to take such comments personally.

All, please keep it on topic or the thread will be closed.
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Old 9th October 2007, 03:47 AM   #23
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Quote:
Originally posted by BWRX

Kanwar, there's no need to YELL or to take such comments personally.
Look Mr.Moderator.................You cannot expect me to believe on a Blatant lie which is wrongly subjected on my country.............Its not a personal thing........OK
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Old 10th October 2007, 11:15 PM   #24
weissi is offline weissi  Europe
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hmm, going very o.t.

one should not be angry about some bad words about the country one is living in. That hasn't anything to do with one personaly. Otherwise, what sould I say, living in a country that 80% of all people all over the world associate with Nazis...

peace!
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Old 18th October 2007, 02:53 PM   #25
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I'm with the Austrian, chill fella's - i take it most of you don't work in gobal companies, understanding W-english (World-English) is a 2 or 3 message event rather than getting it right first time (which many natural english speakers don't do anyhow!)....if this was an english language forum then i'd say nothing and let you get on BUT at the mo (mo=moment) this sounds like a BHP (BHP=Brake Horse Power) thread on a car forum!

danny

p.s. to mimic is to flater, it happens in the product market worldwide you are dreaming if you think it doesn't ...thats why patents are nice BUT not infallible
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Old 19th October 2007, 04:19 AM   #26
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I understand that some of the more seasoned members here have seen, over the years, a number of audio products sold by companies in the Pacific Rim, which, although competent designs, would go just a bit overboard with the hype.

Talk of "Advanced Technology" and "Secret Technology" has been associated before with deceptive marketing, and massaged specs.

So, it is not altogether surprising, that members here would scrutinize anything that makes impressive claims, whether it is actively promoted in the group, or just casually mentioned.

I would not think the 140 volt lower Vin limit should prevent any intrepid North American enthusiast from using this product.
It is obvious it uses an SMPS, (the low-profile case gives it away.)

Sooo,.. any SMPS is bound to full-wave rectify the AC line, somewhere not too far from the AC power input point.
Access the rectifier bridge, and rewire one node to create a voltage doubler. Voila!

That's how a lot of commecrial SMPS powered equipment does it, by doubling 120V to 240V. It's a design handicap to work with the higher currents inherent in 120V systems, so many designers won't go there.

Don't like to break your product warranty? (what's the matter, you're counting on shipping this thing back to Thailand for repair? )

Just build a duplicate AC front end external to the unit, which includes the common- and differential- mode filters and a voltage-doubling bridge rectifier, and feed the DC to the unit's mains receptacle. The SMPS inside will never know the difference.
And the series fuse and inrush-current limiter inside the case, will also be in series with your external unit and protect it.

I'm not sure if RMS units specifications is worth picking at, under the circumstances, we're better off focussing on bigger things...

And before picking at the distortion figure, maybe we should ask about the price. It may put things in perspective.
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Old 19th October 2007, 04:31 AM   #27
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And Oh, yes..

if you do the stunt with the external front end and voltage doubler, you may slightly increase the harmonics fed back into the AC line.

But then again, if you're doing this, you live in a place where many engineers cannot say "regulatory agency compliance" without bursting into laughter.

( and these are the engineers from the power company )
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Old 19th October 2007, 05:16 AM   #28
JesseG is offline JesseG  Canada
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Right on, vectorplane - let's get a little calm(on) sense in this thread.

I am really dissappointed in some of the earlier posts. If you all are so smart, go out an research, design, test, manufacture and sell your own giga-watt, class whatever amp and then you may have a basis for criticism. Of course if you purchased this product and had some difficulty with it...

I am very pleased that one of the designers took the time to provide some information on his work. We should be asking questions that will help us learn and appreciating the answers, not slamming someone from the lofty towers of our own ignorance.

I for one would like to appologise to Michael-Rafia for the inexcusable BAD MANNERS of some of the other posters to this forum.

Quote:
I would not think the 140 volt lower Vin limit should prevent any intrepid North American enthusiast from using this product
Or, you could just wire a 240V circuit from your power pannel to your listening room (I have ).

I would be very interested to know how much this product - say the DTECH-2400 - sells for in Thailand.
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Old 19th October 2007, 04:09 PM   #29
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I cannot comment on the product, I have not used it or tested it.
But one thing I find refreshing: here's one manufacturer who believes that SLIM is SEXY.

it seems most high power amps (especially the home-made ones) are fat and stocky.

Of course it's very difficult to reduce the height of your amp beyond a certain point if you insist on using large toroidal transformers.

I find the attention given to compactness very interesting. And the case hardware seems to be top-noch, with a lot of attention paid to the sheet-metal forming work, all serving to keep size down.

Of course, the Disco and bar setting is not exactly a very demanding test for amplifier THD and S/N ratios.

At the powers used, a large number of things around the room will vibrate (tables, chairs, floor, walls, glassware, fixtures) and multiple delayed interferances from bouncing waves, will produce an inherent level of perceived distortion that will probably mask anything below 0.5THD. And of course, overlapping songs without gaps, will take care of the S/N ratio.
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Old 19th October 2007, 04:50 PM   #30
Eva is offline Eva  Spain
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In a disco environment (depending on venue size) a hundred or thousand people talking loud and shouting will take good care of things such as S/N ratio and stereo cross-talk You actually need an efficient PA and powerful amplifiers to make the music dominate over the ambient noise. In these circumstances, what you need is moderate distortion until very loud and bullet-proof limiters to prevent the system from self destructing when the party is going to an end and the DJ sets to maximum all volume and gain knobs for the few last songs.
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